A stochastically curtailed two-arm randomised phase II trial design for binary outcomes

Randomised controlled trials are considered the gold standard in trial design. However, phase II oncology trials with a binary outcome are often single-arm. Although a number of reasons exist for choosing a single-arm trial, the primary reason is that single-arm designs require fewer participants than their randomised equivalents. Therefore, the development of novel methodology that makes randomised designs more efficient is of value to the trials community. This article introduces a randomised two-arm binary outcome trial design that includes stochastic curtailment (SC), allowing for the possibility of stopping a trial before the final conclusions are known with certainty. In addition to SC, the proposed design involves the use of a randomised block design, which allows investigators to control the number of interim analyses. This approach is compared with existing designs that also use early stopping, through the use of a loss function comprised of a weighted sum of design characteristics. Comparisons are also made using an example from a real trial. The comparisons show that for many possible loss functions, the proposed design is superior to existing designs. Further, the proposed design may be more practical, by allowing a flexible number of interim analyses. One existing design produces superior design realisations when the anticipated response rate is low. However, when using this design, the probability of rejecting the null hypothesis is sensitive to misspecification of the null response rate. Therefore, when considering randomised designs in phase II, we recommend the proposed approach be preferred over other sequential designs.     

Optimal classification scores based on multivariate marker transformations

AStA Advances in Statistical Analysis - Modern science frequently involves the study of complex relationships among effects and factors. Flexible statistical tools are commonly used to visualize...     

Unwanted sexual experiences and sexual risks in gay and bisexual men: Associations among revictimization,substance use,and psychiatric symptoms

The data set of 2,182 gay/bisexual men's month‐long sexual diaries collected by the United Kingdom Socio‐sexual Investigations of Gay Men and Aids (Project SIGMA) was used to analyse the extent to which acts of anal intercourse (AI) are distributed among gay men, using the Lorenz/Gini methodology for measuring concentration. Most individuals (60%) who engage in AI do so only once or twice a month, but there is a long tail of those who do it much more. In terms of the amount of AI acts, one tenth of the individuals are performing half of the acts of AI. The Gini coefficient of concentration is high (0.55). Factors most affecting rates and concentration of risk behaviour include relationship status, HIV sero‐status and concordant/discordant partner status.     

Value Accentuation or Convergence: Analysis of the Pattern and Process of College Student Change

Abstract

College student value change was analyzed for individual and group value accentuation or convergence among a longitudinal panel study of students in a traditional, large liberal arts college and a small, innovative living-learning subenvironment. Initially students in the innovative environment were more liberal, socally conscious, culturally sophisticated and intellectually oriented than their counterparts in the traditional setting, and, after two years, accentuation of these group differences had occurred. However, these group differences were not the result of accentuation of individual differences. Instead, increases in the student values were linked to interaction with peers and faculty on related topics and these patterns of interaction were more likely to occur in the living-learning subenvironment. Finally, those students who initially were lowest on a value and who frequently interacted with faculty or peers on related topics tended to experience the greatest value change.     

Modernization and the Demographic Transition: Cross-Sectional and Longitudinal Analyses of a Revised Model

Abstract

We specify a revised model of the demographic transition which accounts for national fertility levels and changes over the past two decades. The model includes cultural, geographic, demographic and family planning program variables, in addition to a measure of national socio-economic modernization. Using crude birth rates for 117 countries, we operationalize and then apply the revised model to 1974 rates, and then test a longitudinal model of 1955–59 to 1974 change in rates. A final model for 81 less developed nations from the original set of 117 countries includes a measure of family planning program effort. Including this highly significant measure in a model of 1955–59 to 1974 change results in further evidence favoring modification of the traditional demographic transition model. Implications for the future course of fertility in underdeveloped countries are discussed.     

An examination of sexual strategies used by urban southern and rural Midwestern university women

The purposes of this study were (a) to determine whether women's use of persuasion, non‐physical coercion, and physical force strategies to obtain sex from a man varied between U.S. women from an urban Southern and rural Midwestern university and (b) to determine if sexual behavior history and early courtship behavior affected the use of these strategies (or not using any strategy). Women from the Midwest and the South did not differ in their use of sexual strategies. There were, however, other variables that accounted for differences in women's use of sexual strategies. Women who used persuasion strategies had fewer lifetime sexual partners than women who used any other strategy. Women who used physical force strategies reported a lower age at first intercourse and more early courtship behaviors than all others. Overall, the results indicated that sexual strategies are related to sexual behavior history and early courtship behaviors rather than cultural setting or demographics.